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The most important elements of ab initio calculations of x-ray-absorption fine structure (XAFS) are studied. To obtain accurate results without ad hoc adjustable parameters, we find it essential to include (i) curved-wave effects,(ii) a complex, energy-dependent self-energy,(iii) an approximate molecular potential, and (iv) a fixed energy reference for the photoelectron wave number. Based on these findings, an automated code has been developed for ab initio calculations of single-scattering XAFS, in which curved-wave effects are treated exactly in terms of effective backscattering amplitudes, inelastic losses and self-energy shifts are incorporated with use of a Hedin-Lundqvist self-energy, an automated relativistic overlapping-atom muffin-tin potential is used, and the energy threshold is estimated from electron-gas theory. The efficiency of the code is made possible by analytic expressions for the Hedin-Lundqvist self …